1. Field of the Invention
The invention relates to an expansion sheet for a rotary electric machine, a stator for a rotary electric machine using an expansion sheet for a rotary electric machine, and a manufacturing method of a stator for a rotary electric machine.
2. Description of Related Art
A vehicle such as a hybrid vehicle or an electric vehicle is typically provided with a rotary electric machine capable of functioning as both a motor and a generator. The rotary electric machine typically includes a stator, and a rotor that rotates with respect to the stator, with a predetermined gap created therebetween. The stator includes a stator core, and a plurality of coil conductors that are wound around the stator core.
When the rotary electric machine functions as a motor, direct current (DC) power from a power supply such as a secondary battery or a fuel cell is stepped up to a desired voltage using a step-up converter as necessary, and converted to a polyphase alternating current (AC) power by an inverter. The resultant current then flows through the coil conductors that are wound around the stator, causing the rotor to rotate. On the other hand, when the rotary electric machine functions as a generator, rotation of the rotor causes current to flow through the coil conductors that are wound around the stator. The power obtained at this time is charged to the secondary battery or the like as regenerative power, or is supplied to electronic equipment such as auxiliary equipment, and consumed as driving power.
Slots are formed in the stator core of the stator for the rotary electric machine. The coil conductors are housed in these slots. At this time, an insulating layer for insulation needs to be formed between the inner peripheral surface of each slot and the corresponding coil conductor. One example of a method for providing this insulating layer in the slot is a method using an insulating sheet.
Japanese Patent Application Publication No. 59-117435 (JP 59-117435 A) relates to a high-voltage coil of a rotary electric machine, and describes housing, in a groove of an iron core, a coil conductor that is wound surrounded by a slot liner having a conductive foam layer on both sides of graphite paper.
Japanese Utility Model Application Publication No. 01-166780 (JP 01-166780 U) relates to a rotary electric machine for a compressor, and describes installing insulating paper having a trilaminar structure in which surface layers of different thicknesses are formed on both sides, such that the thin surface layer is on a coil side and the thick surface layer is on an iron core side.
Japanese Patent Application Publication No. 61-277347 (JP 61-277347 A) relates to motor insulating paper of a compressor, and describes slot insulating paper in which first insulating paper material that is extremely strong mechanically is laminated to second insulating paper material that is heat resistant.
Japanese Patent Application Publication No. 2002-262500 (JP 2002-262500 A) describes a rotary electric machine in which a stator coil is supported by a bimetal in which a plurality of sheets of material having different coefficients of thermal expansion are laminated together.
Japanese Patent Application Publication No. 2010-259316 (JP 2010-259316 A) relates to a stator for a rotary electric machine, and recites that, in an adhesive sheet that has a trilaminar structure formed by an adhesive layer that is laminated to each side of an insulating layer, and resin that forms the adhesive layer may have expandability.